linux-kernel - [tip:locking/core] locking/qspinlock: Remove unnecessary BUG

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Date:   Wed, 27 Feb 2019 23:02:01 -0800
From:   tip-bot for Waiman Long <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        paulmck@...ux.vnet.ibm.com, hpa@...or.com, mingo@...nel.org,
        longman@...hat.com, akpm@...ux-foundation.org,
        torvalds@...ux-foundation.org, will.deacon@....com,
        peterz@...radead.org
Subject: [tip:locking/core] locking/qspinlock: Remove unnecessary BUG_ON()
 call

Commit-ID:  733000c7ffd9d9c8c4fdfd82f0d41956c8cf0537
Gitweb:     https://git.kernel.org/tip/733000c7ffd9d9c8c4fdfd82f0d41956c8cf0537
Author:     Waiman Long <longman@...hat.com>
AuthorDate: Sun, 24 Feb 2019 20:14:13 -0500
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 28 Feb 2019 07:55:38 +0100

locking/qspinlock: Remove unnecessary BUG_ON() call

With the > 4 nesting levels case handled by the commit:

  d682b596d993 ("locking/qspinlock: Handle > 4 slowpath nesting levels")

the BUG_ON() call in encode_tail() will never actually be triggered.

Remove it.

Signed-off-by: Waiman Long <longman@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: Will Deacon <will.deacon@....com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: https://lkml.kernel.org/r/1551057253-3231-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/locking/qspinlock.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index 21ee51b47961..5e9247dc2515 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -124,9 +124,6 @@ static inline __pure u32 encode_tail(int cpu, int idx)
 {
 	u32 tail;
 
-#ifdef CONFIG_DEBUG_SPINLOCK
-	BUG_ON(idx > 3);
-#endif
 	tail  = (cpu + 1) << _Q_TAIL_CPU_OFFSET;
 	tail |= idx << _Q_TAIL_IDX_OFFSET; /* assume < 4 */